In the next few years, multimedia applications will in full scale enter the world of cellular communications. To support new services, which will set new demands on the infrastructure for radio communications, a new wireless communication system needs to be developed. To meet these demands of wireless mobile communication in a true multimedia environment, high speed packed data and Internet bearer services play major roles.
The future of mobile telephony is now being determined by the global standardization work conducted by public authorities and the industry. Wireless Application Environment (WAE) is a result of the Wireless Application Protocol (WAP) efforts to promote industry-wide standards and specifications for developing applications and services that operate over wireless communication networks. WAE specifies an application framework for wireless devices such as mobile telephones, pagers and PDAs (Personal Digital Assistants). The framework extends and leverages other WAP technologies, including Wireless Transaction Protocol (WTP) and Wireless Session Protocol (WSP), as well as other Internet technologies such as scripting and various content formats. The effort is aimed at enabling operators, manufacturers and content developers to meet the challenges of implementing advanced differentiating services and applications in a fast and flexible manner.
WAE adopts a model that closely follows the WWW (World Wide Web) model. All content is specified in formats that are similar to the standard Internet formats. The content is transported using standard protocols in the WWW domain and an optimized protocol similar to HTTP (Hyper Text Transfer Protocol) in the wireless domain. The WAE architecture allows all content and services to be hosted on standard Web origin servers. All content is located using WWW standard URLs (Uniform Resource Locators).
WAE enhances some of the WWW standards in ways that reflect the device and network characteristics. WAE extensions are added to support Mobile Network Services such as Call Control and Messaging. Careful attention is paid to the memory and CPU processing constraints that are found in mobile terminals. Support for low bandwidth and high latency networks is included in the architecture as well.
WAE assumes the existence of a gateway functionality responsible for encoding and decoding data transferred from and to the mobile client. The purpose of encoding content delivered to the client is to minimize the size of data sent to the client over-the-air as well as to minimize the computational energy required by the client to process that data. The gateway functionality can be added to origin servers or placed in dedicated gateways.
In the mobile stations of the mobile network, a software or device, called user agent, is provided that interprets a network content referenced by a URL. This may include textural browsers, voice browsers, search engines and the like.
The user agent is connected to the mobile network using dedicated signaling connections. The origin server communicates with the client using the WAP protocol stack, may be connected to the mobile network and is responsible for deploying content to its clients. In the case of call-handling, for example, the mobile network sets up the call to the client, the server delivers the event-handling content, and the user agent invokes the event-handler content and manages the presentation of the call-handling service to the user.
However, in case a circuit switched data bearer (CSD bearer) is used for transmitting data between the server and the mobile client, the call set-up time is relatively high, eg. 15-60 s depending on the solution. Thus, the end user has to wait for the connection and cannot use its mobile phone.
Moreover, the user agent may have a very rigid and real-time context management. For example, the user agent may drop outdated (or stale) events, may not place intermediate results on the history stack, and may typically terminate after the event is handled. Hence, the success of content delivery (eg. handling of call control) is, to some extent, dependent on the operator's ability to access and control the speed of the mobile network.
Furthermore, when a mobile terminal communicates over an IP bearer by using e.g. CSD or GPRS (General Packet Radio Service) with an external gateway such as a WAP gateway, the MSISDN of the mobile terminal is not known by the gateway. Therefore, the operator may only charge the user for the used airtime (e.g. in case of a CSD connection) or for the sent data packets (e.g. in case of GPRS connection). However, a charging per used service is not possible, since the required IP address is usually allocated dynamically by an access server (e.g. in case of the CSD connection) or by an SGSN (Serving GPRS Support Node). Hence, an association between the MSISDN and the IP address is not available.